Hi Edward,

BOMA 1980 utilizes a very simple methodology in determining Usable and Rentable areas. There is no subtraction per se in BOMA 1980. Rather, there is simply no inclusion. The Usable Area of an office simply does not include the Major Vertical Penetrations (stairs, elevators, shafts, etc) or the Floor Common Areas that you mentioned. The Rentable Area is determined by measuring the area of the entire floor except for the Major Vertical Penetrations. The floor r/u ratio is then determined by dividing the floor's rentable area from the floor's usable area. The result is then multiplied to each tenant's usable area on that floor in order to determine each tenant's proportionate share of Floor Common Area and each tenant's rentable area. On a single tenant floor (or in your case a single tenant building), the calculation of the R/U ratio is unnecessary since there is no proportionate allocation of Floor Common Area required. Simply measure the usable area and rentable area as described above.

It should be noted that in a single tenant building, the Construction Gross Area may be used for leasing. The Construction Gross Area is measured to the outside finished surface of permanent outer building walls on all floors of the building, including basements, penthouses, etc.